Currently measurements of tibial-calcaneal or vertical-calcaneal alignment are performed using two-dimensional standard radiographs and applying various radiographic protocols, such as the long-leg view, Meary, Saltzman, or Cobey. See, for example, Mendicino, R. W., Catanzariti, A. R., John, S., Child, B. & Lamm, B. M., “Long leg calcaneal axial and hindfoot alignment radiographic views for frontal plane assessment,” J. Am. Podiatr. Med. Assoc. 98, 75-78 (2008); Saltzman, C. L. & el-Khoury, G. Y., “The hindfoot alignment view,” Foot Ankle Int. 16, 572-576 (1995); Strash, W. W. & Berardo, P., “Radiographic assessment of the hindfoot and ankle,” Clin. Podiatr. Med. Surg. 21, 295-304, v (2004); and Tuijthof, G. J., Herder, J. L., Scholten, P. E van Dijk, C. N. & Pistecky, P. V., “Measuring alignment of the hindfoot,” J. Biomech. Eng. 126, 357-362 (2004). Each of these methods uses two dimensional data obtained from radiographic scan and bases all the foot ankle alignment assessments off of those scans. In each case, the protocols do not take into account the relation of the forefoot with the hindfoot. Instead, they only provide a measurement of the hind-foot-ankle-leg alignment. As such, it is not a complete-foot-ankle alignment measurement.
The inventors have determined that the existing methods' failure to take into account the measurement of the forefoot results in less precision due to poorly reproducible radiographic protocols. Also, since the prior methods rely solely on hindfoot measurement, the accuracy of the overall measurement geometrically depends on the rotation of the lower limb.
A need therefore exists for an improved method for providing foot-ankle alignment measurement.